Few chief justices have had as good a run as John Roberts has with the center-left political class in recent days: a man who would have been eviscerated as an ideological disaster had he voted to strike down any part of the Affordable Care Act has instead become an unlikely American hero in many precincts — for now.

In making himself the fifth and deciding vote to uphold President Obama’s health-care reform (possibly changing his mind along the way), Roberts has shown himself a chief justice with a sense of history. By and large the chiefs who fare well down the years are the ones who prove effective politicians, men who understand that the Supreme Court is not a marble Brigadoon but a fundamentally political institution whose standing with the nation is fluid, not fixed.

John Marshall grasped this early on. Marshall is one of those Founders who remains more monumental than mortal — a fact that might surprise him and his contemporaries, for in real time the third chief justice established the principle of judicial review without forcing an existential showdown with presidents ranging from Thomas Jefferson to Andrew Jackson.

In Marbury v. Madison, Marshall ostensibly ruled against Jefferson’s Republican administration — but really didn’t, in fact, for Marshall swerved in his opinion from directing the executive branch to do something it was refusing to do by declaring the provision of the 1789 Judiciary Act under which the plaintiff had brought the case unconstitutional. It was brilliant, establishing a principle by avoiding a crisis in practice.

Earl Warren — himself a former Republican governor of California — knew that integrating public schools was so incendiary an issue that only a unanimous court could do it. In the early 1950s, then, he forged a 9-0 vote to end separate-but-equal. Warren knew that integration was going to be difficult enough to bring about, and that a politically unified court would be best for the country.

And now Roberts has added a chapter to this history by insisting that the court defer to the elected branches, essentially arguing that it is not the job of the court to protect the people from the consequences of their political choices.

Which is, in its way, a political choice all its own. In a nation still skeptical of a court that stopped the Florida recount in Bush v. Gore in 2000, Roberts decided to act in the Marshall-Warren tradition of protecting the court’s standing by declining to exacerbate an already-tense political atmosphere. A Republican chief throwing out a Democratic president’s legislative achievement would have further polarized the nation. For now, at least, we’re only as polarized as we were before the decision.